October 14, 2007

Fitchifying Language Change

This is the second of two posts today on the fitchification of
aspects of historical linguistics. The first
focused on a misunderstanding of the history of (modernish)
linguistics in Tecumseh Fitch's recent Naturearticle.
This one is on his odd views about the nature of language change.
Some are just simple mistakes, or at best uncritical acceptance of
highly controversial views on the topics he's addressing. Examples
are his claim that Proto-Indo-European was spoken `some 10,000 years
ago' (the prevalent view among Indo-Europeanists, who are the people
who have the linguistic evidence, is more like 6,000 years); his
belief that the family tree of related languages was `the crowning
achievement' of 19th-century historical linguistics (see comments in
my earlier fitchification post today); and his belief that people
`don't generally invent words or grammatical forms'. On this last one, anyone who was
ever a teenager, or who ever even met one, should know better -- in
addition to the world of teenage slang and all those corporate
inventors of terms for new products, consider novel constructions
like the -f***in'- infix in words like
abso-f***in'-lutely. (No, of course those
asterisks aren't necessary on an enlightened forum like Language Log.
I just think they're cute.) And community-wide examples of
deliberate linguistic changes, at all levels of linguistic structure,
are turning up quite frequently these days -- changes, that is, that
alter an entire language, typically in a small speech community. But
Fitch also reveals a more interesting misunderstanding in his
conception of what language change, especially lexical change,
is.

The problem is that Fitch seems to be conflating three very
different change processes. First, there's lexical replacement, as
when early English hound was replaced by
dog as the generic term for the animal, or
when Old English deer was replaced by the
borrowed word animal as a generic term for
a beast. Second, there's analogic regularization, as when the verb
fly, without giving up its inherited past
tense flew, acquired an alternative past
tense form flied (with a slightly different meaning) in baseball expressions
like he flied out to left field. There
are also occasional analogic changes in the opposite direction, away
from global regularization, as when wear
changed from a weak past tense, which would have become weared if it had survived into Modern English, to a
strong past tense wore on the analogy of
rhyming verbs like tear, swear, and bear; it is not true that analogic change always
favors the majority pattern, so Fitch is wrong when he says that
irregular verbs `remain only as irregular residues'. And third,
there is sound change, which (according to the regularity hypothesis,
which dates back to the late-19th-century Neogrammarians) is blind to
considerations of morphology, semantics, and -- crucially in Fitch's
context -- frequency.

Fitch emphasizes frequency of occurrence of particular words
because that is the focus of the two articles he is surveying in his
essay (see Mark's
post of a few days ago for the links). One set of authors argues
that the most frequent words resist analogic regularization; the
other set argues that the most frequent words resist change, at least
in Indo-European languages. Fitch acknowledges that the `realization
that frequency of use has a significant role in language change is
nothing new', but claims that `the use of sophisticated methods...to
quantify these relationships is an important step forward'. He does
not say why it's an important step forward, but never mind.
It's nice to have quantitative evidence to support what historical
linguists have known for a hundred years or so, and it's not
necessarily a trivial result.

Some of Fitch's examples are unfortunate choices as illustrations
of his thesis. He says that `high-frequency English verbs retained
their ancestral irregular state ("go/went" or "be/was")'. It depends
on what he means by `ancestral', of course, but he might be
interested to know that some of the irregularities in these two verbs are not
all that old. Old English had a regular past tense for go; the earliest example of went given in the Oxford English Dictionary is
from 1484, five or six hundred years after the earliest documented
Old English. So this is another case like wear, where a regular verb has become irregular over
time. The history of be is more
complicated. According to the OED, the modern paradigm of
this verb is an amalgam of three different Proto-Indo-European verbs
-- PIE *es- `be' in the present tense
(am, are, is, are, with analogic changes
merging several forms); PIE *bhew-
`become' in non-finite forms (be, being);
and PIE *wes- `remain, stay, continue to
be' in the past tense (was, were, again
with several analogic mergers). The inherited verb for `become' was
still a distinct verb in Old English, and only later merged with the
other two combined verbs as the infinitive. So this most irregular
of Modern English verbs, like go and wear, has in fact become more irregular in
recorded history. Of course these quasi-counterexamples don't affect the
statistical patterns that show that frequency affects the tendency for regular formations to spread analogically at the expense of irregular formations. They do
suggest that it's a good idea to check one's facts.

Fitch's most serious mistake, though, is not his choice of
examples that don't show what he thinks they show. His most
hair-raising error is the flat assertion that `frequently used words
are resistant to change'. This is clearly true if the type of change
is analogic regularization. It may or may not be true of lexical
replacement (and I admit that I haven't yet read the articles he
refers to, to see if they make any distinctions according to the type
of lexical change); it won't be surprising if it holds there too.
But it most certainly is not true of lexical changes due to sound
change. The Neogrammarians' hypothesis that sound change is
inevitably regular runs into problems, primarily (but not entirely)
having to do with the differential spread of sound changes through a
speech community. However, the fact that the Comparative Method,
which rests heavily on the regularity hypothesis, has proved to be
effective in the establishment of language families and the
reconstruction of proto-languages for all but a very small subset of
the thousands of human languages is in itself evidence that regular
sound change is the norm, not the exception. And regular sound
change is indeed blind to frequency and all other nonphonetic
contextual factors. So it is nonsense to say that frequent words
resist change unless one qualifies the statement to exclude regular
sound change. When Fitch speculates that `new phonological forms
might arise less often for high-frequency words because errors of
perception, recall or production are less common for frequently used
words', his reference to perception and production clearly includes
lexical changes due to sound change. He himself does not mention
pronouns. A member of one of the two author sets for the quantitative Nature articles (I didn't catch
the interviewee's name), interviewed the other day on a BBC radio program, did cite
pronouns as examples of unlikely-to-change words, and certainly they
are among the most frequent words in Indo-European languages. But
pronouns aren't all that unlikely to change; see this earlier
Language Log discussion
of the `super-stable pronoun' hypothesis (it's a recurring
theme).

I've been critical of Fitch's article, so I should emphasize one
point on which we agree: he is quite correct (if unoriginal) to say
that an `adequate explanation for [what he quaintly calls]
glossogenetic phenomena must incorporate individual and collective
levels of description, and show why they are necessarily related'.
I'm skeptical about the likelihood that statistical analyses imported
from other disciplines will solve this difficult problem. It's not
that statistical explorations of relationships between frequency and
lexical replacement and/or regularization, and in other areas of
language change as well, should be ignored; they have produced very
interesting results in a variety of domains. But errors of the sort
that Fitch makes show clearly that new approaches to historical
linguistic analysis will be successful only to the extent that they
take into account the results of historical linguistic investigations
over the past hundred and fifty years or so. Failing to learn
something about a field one wishes to contribute to is all too likely to
lead to reinvention of the wheel at best, and to a garbage in/garbage
out problem at worst.